WASHINGTON -- To his friends, Neil E. Prescott was a "gentle giant" -- a physically towering young man with a background in computers and electronics and a sarcastic, even biting, sense of humor that people close to him knew to shrug off as innocuous.

But police say they had no choice but to take it seriously when Prescott threatened to shoot up his workplace and referred to himself as "a joker," comments that raised particular alarm in the wake of the recent mass shooting at a Colorado theater during the latest Batman movie. The man accused in those shootings dyed his hair reddish-orange, and New York Police Commissioner Ray Kelly has said the man called himself the Joker -- a reference to Batman's nemesis.

Prescott, 28, was taken into custody early Friday at his apartment in Maryland, where officers found several thousand rounds of ammunition and a cache of about two dozen weapons including semi-automatic rifles and pistols. He was receiving an emergency psychiatric evaluation at a hospital.

Two friends said Saturday that they couldn't imagine that Prescott, who was in the process of being fired or already had lost his job, intended to be taken seriously when he allegedly told a supervisor: "I'm a joker and I'm gonna load my guns and blow everybody up."

"Neil's the kind of guy who had the ability to say the wrong thing at the wrong time and not mean anything by it. So to him, he thinks it's funny," said Wesley Weber, who said his friend, at 6 feet 7 inches, was a "gentle giant" prone to bouts of exaggeration and inappropriate jokes who "talked big but didn't walk the walk."

Another friend, Mike Cochran, said Prescott has a history of wearing T-shirts with sarcastic, provocative and even inflammatory messages and is "no stranger to sarcasm regardless of political correctness." When first approached by officers, police say, Prescott was wearing a shirt that said "Guns don't kill people. I do."

"The Neil I know made those comments sarcastically in an environment where he felt he could make them without being taken seriously," Cochran said in an email.

Friends say that over the years, Prescott had shown deep interest in hobbies such as computer software, electronics and ham radio. His clique of friends at one time gathered at parties to play multi-player video games and consume the highly caffeinated Jolt cola, Weber recalled. A sometime disc jockey, he'd also spin house music at Baltimore nightclubs and was the DJ for Cochran's bachelor party in 2005.

In recent years, though, he'd cultivated a passion for collecting firearms. He'd practice his shot at the training range, friends said, and communicate online with fellow gun enthusiasts about the ins and outs of firearm equipment and gun laws. At least some of the firearms recovered from his apartment in Crofton, near Annapolis, appear to have been legally owned, authorities said.

A search for Neil Prescott on a website that tracks users' online activities led to a profile that appears to be him on mdshooters.com, a website for Maryland gun hobbyists. On it, he trades advice about firearms with a display of technical know-how while at times expressing concern about break-ins near his apartment and detailing interactions with the police.

Cochran, who also posts on the site, said he doesn't know when Prescott started his gun collection but that he had been anxious about home invasions. He said he received one message from Prescott last November that said, "Might be sleeping in tomorrow, just had a suspicious male at my door. Notified PD but am gonna be lookin out tonight. Some crazy breakins near me recently."

In March, he provoked a spirited back-and-forth on the site when he complained that two police officers responding to a possible break-in at a nearby apartment "told me never to answer the door on my own property carrying." He said he called a sergeant to complain about the directive.

Last week, he was still on the site, talking with fellow users about 30-round magazines and boasting about his night-vision goggles.

"During the power outage i spent lots of time loading mags and mounting lights, when the zombie apocalypse comes i'll be ready," he wrote.

Maryland state court records for Prescott list only a speeding ticket in 2007. It wasn't immediately clear if he had a lawyer.

Police say Prescott, an employee of a subcontractor for software and mailroom supplier Pitney Bowes, made the threats during two Monday morning phone conversations with a supervisor. The supervisor, who declined to comment Saturday to a reporter who came to his house, said the comments made him afraid, especially because he was aware of Prescott's weapons' cache.

Prescott at one point said he wished to see his supervisor's "brain splatter all over the sidewalk," but also acknowledged that he shouldn't be saying such things over the phone, according to a search warrant applications. The threats were reported to the police, who paid an initial visit to Prescott's apartment on Thursday before taking him into custody Friday morning.

Cochran said he's known Prescott since 2001, when they were colleagues at a technical support outsourcing company. He said Prescott was a network engineer.

"With his skill set and education he would have had no problems finding other work with good pay. Neil did not at any point indicate to me that he had problems with where he was working," Cochran wrote.

Pitney Bowes spokeswoman Carol Wallace said Prescott had not been on any company property in at least four months. It wasn't clear why he was losing his job.

Weber said he thought the remark was inappropriate, but that it was bound to receive more attention now than it may have years ago, especially one week after the Colorado shooting.